The invention relates to a method and apparatus for impulse charging of an internal combustion engine.
An important reason for charging a combustion engine is that a given performance or a given torque can be produced with a relatively smaller engine than otherwise would be required, thus yielding advantages in weight, space, and usage considerations. A further advantage is that the charging offers an additional parameter for influencing the charging preparation and the combustion process, whereby the thermodynamic efficiency and/or the carbon monoxide content in the exhaust can be advantageously influenced.
In practice, exhaust gas turbo charging has been effected by means of a mechanical charger driven by a crankshaft. There have regularly been efforts to develop a so-called impulse charging by which a flow regulating piece, disposed within an inlet duct upstream of the inlet valve, is cyclically closed such that, during the intake movement of the piston with an open inlet valve downstream of the flow regulating piece, an underpressure is produced. If the flow regulating piece is then moved into its open position as the underpressure is produced, the underpressure acts to accelerate the released charging load, which thereupon flows with a high impulse into the combustion chamber to therein effect a large loading. Rotary cam pushers, linearly movable pushers, and similar structures have been used as the flow regulating piece which cyclically closes the inlet duct but such structures have required exterior drive means to effect their movement as well as a relatively long window of time to effect complete opening of the inlet duct, whereby the efficiency of the impulse charging has been detrimentally influenced.
An object of the present invention is to provide a method and apparatus for impulse charging of an internal combustion engine which achieve a highly efficient impulse charging through simple operation and reduced energy consumption.
Another object of the present invention is to provide a method and apparatus for impulse charging of an internal combustion engine which uses the energy of the charging flow itself to facilitate the movement of the flow resistance element into its open position in which it permits the full cross section of the inlet duct to be available for flow. This is advantageous in that the movement of the flow resistance element can, on the one hand, be effected in a relatively rapid movement and, on the other hand, only a relatively small amount of additional external energy is required. These advantages raise the efficiency of the impulse charging.
In accordance with the present invention, the foregoing and other objects are attained by a method and an apparatus which comprise disposing a flap as a flow resistance element in an inlet duct which is relatively rapidly movable to permit a heretofore not attained quick availability of the full cross section of the inlet duct for flow of the charging load therethrough, whereby this capability to provide the quick availability of the inlet duct for flow permits effective utilization of the pre-opening underpressure to create an impulse charging. The full cross section of the inlet duct, which is made available for flow due to the precipitous movement of the flap, ensures that there is only relatively little loss of flow. The method and apparatus of the present invention provide a magnetic surface disposed in the inlet duct which is selectively energizeable to retain the flap in its closed position and means for resiliently biasing the flap into its closed position so as to advantageously minimize the energy required to energize the magnetic surface.
The method and apparatus of the present invention are suitable for inlet ducts as well as exhaust ducts of internal combustion engines which may be configured as Otto-cycle engines as diesel engines and which may operate as two- or four-cycle engines. The mixture preparation can be effected through induced injection, direct injection or other injection methods.
Further objects, features, and advantages of the invention will be apparent from the following description of a preferred embodiment.